Not the Otton frog, but something close to it. See the original source link for a photo. (Shutterstock)

(Newser)
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Meet the most badass frog in the pond: The Japanese Otton frog has what amounts to spiked thumbs, reports LiveScience. The scientist who made the discovery says the extra bony digit is used to help the male hang on during mating but also for fighting other males. It's apparently not a lethal weapon, because the boys seem to take care not to poke each other in the eye or ear drums. Discover has a great photo here—and it also uses the term "flick-knives" to describe the weaponry.

"While the pseudo-thumb may have evolved for mating, it is clear that they're now used for combat," says the University of Tokyo scientist who made the find. "The males demonstrated a jabbing response with the thumb when they were picked up, and the many scars on the male spines provided evidence of fighting." A group of African frogs has retractable claws, but those frogs don't have the extra "psuedo-thumb." Advantage, Otton.

i like rare frogs. i like nature. i believe it is in our best interests to protect all those creatures that we know to inhabit the earth, and those that we have so far not become aware of. i like nature. i like to watch the interaction between spider and prey, dung beetles breaking down the dog poop in the neighborhood, even the angry yellow jackets who once attacked me when unbeknownst to me i sprayed with water a rosemary bush that was their safe haven. i couldn't enter my house for quite a while, as they buzzed about looking for the armed attacker. lol. nature is wondrous. enjoy. stop and watch. you might be amazed.